Final answer:
Dogs of all ages and breeds are eligible for the longitudinal study of the Dog Aging Project.
Step-by-step explanation:
The Dog Aging Project is a longitudinal study that aims to investigate the aging process in dogs and understand the factors that contribute to longevity and health.
All dogs, regardless of age or breed, are eligible to participate in the study. Puppies, senior dogs, and dogs of any breed can be included in the research.
The study is interested in examining a wide range of dogs to gather diverse data and insights on aging. By including various types of dogs, researchers can understand the aging process more comprehensively and identify potential factors that influence lifespan and health.